Handling Missing Values in pandas: dropna, fillna and What Each One Claims
By Michael Nocito , data analyst · Published August 8, 2026 By the end of this page you can count what is missing and where, choose between dropping…
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Where to Find Free Datasets to Practice With (And How to Pick One)
By Michael Nocito , data analyst · Published August 8, 2026 By the end of this page you will have a shortlist of places that hold millions of free d…
Excel Tables vs Ranges: What Ctrl+T Actually Changes
By Michael Nocito , data analyst · Published August 8, 2026 By the end of this page you can turn a list into a real Excel table, write formulas that…
Excel Dynamic Arrays: FILTER, UNIQUE and SORT in One Formula
By Michael Nocito , data analyst · Published August 8, 2026 By the end of this page you can pull a distinct list out of a column, extract every row…
Excel Drop Down Lists and Data Validation, and the Paste That Removes Them
By Michael Nocito , data analyst · Published August 8, 2026 By the end of this page you can put a dropdown on a column in about a minute, keep its l…
How to Connect Python to a SQL Database (Straight Into a DataFrame)
By Michael Nocito , data analyst · Published August 8, 2026 By the end of this page you will run a SQL query from Python and get back a pandas DataF…
How to Connect Excel to a SQL Database (And Stop Pasting)
By Michael Nocito , data analyst · Published August 8, 2026 By the end of this page your spreadsheet will pull its numbers straight from a database,…
How to Review AI-Generated SQL Before You Trust the Number
An AI assistant will write you a query in ten seconds, the query will run, and the number that comes back will look completely reasonable. This page…
pandas GroupBy: How to Summarize a DataFrame Without Losing Track of Your Rows
By Michael Nocito , data analyst · Published August 7, 2026 By the end of this page you can take a DataFrame, summarize it by any column or combinat…
Excel Just Summed Your ID Numbers and Said Nothing
By Michael Nocito , data analyst · Published August 7, 2026 This article gives you the test that catches the most common beginner mistake in pivot t…
Your Tableau Dashboard Needs Two or Three Views, Not Eight
By the end of this page you can look at a folder of eight finished sheets and say which two or three belong on the dashboard, which one goes in the…
What Is Data Analysis?
By the end of this page you will have done a real piece of data analysis. It is a small one, on paper, with arithmetic you can do in your head. You…
How to Verify an AI Agent Actually Did the Work
An AI agent tells you the work is done. Here are five checks that show whether it is. Each check takes a minute or two. Each one looks at the thing…
How to Build a Tableau Dashboard and Story
By the end of this guide you will have a published Tableau dashboard and a three-point story, built on a real dataset. It lives on a public URL you…
Technical Tenacity: What to Do When the Tools Fight Back
This guide gives you a repeatable loop for the days when nothing works, and four true stories showing it used on real problems. Here is what a worki…
How SQL and Python Work Together in Data Analysis
Every data analyst job posting asks for SQL and Python. That raises an honest beginner question nobody seems to answer directly. If both work with d…
Why Exploratory Data Analysis Matters
Exploratory data analysis , or EDA, is the habit of looking at your data before you compute anything from it. This guide covers what to look at, the…
Your Data Is Never Fully Clean, and Analysts Ship Anyway
Analysts ship work that still has flaws in it. They do it by documenting every imperfection and making it defensible . This guide covers how, at the…
Operationalization: Turning Fuzzy Questions Into Measurable Definitions
Business questions arrive fuzzy. Popular. Churned. Engaged. Hidden gem. Someone has to turn that fuzz into an exact rule before a single query can r…
Data-Driven Thresholds: Picking Cutoffs You Can Defend
Every real analysis runs into the same quiet decision, over and over: where do you draw the line? How many reviews before a rating is trustworthy? H…
How to Handle Large Datasets
You double-click a data file and Excel spins, freezes, or tells you it cannot open it. Real-world datasets are often far bigger than a spreadsheet c…
Your First Analysis Is the Role You Are Targeting
By the end of this you will have picked one role and know the next five things to read. That is the whole point. People spend six months learning to…
코드베이스를 다 이해 못 해도 괜찮다 — 부분적 이해를 위한 변호
이 글은 제 블로그에 처음 발행되었습니다 · Originally published at dbhyeong.github.io Sean Goedecke의 'In defense of not understanding your codebase'(2026-07-11)를 읽고 정…
Who actually feels lost about Germany's new automatic platform and crypto tax reporting? (a pandas cut)
Since January 2026, if you sell on eBay or Vinted, rent a room on Airbnb, or trade on Coinbase or Bitpanda, the platform now reports your income str…
Europe's brain drain: the biggest loser flips when you normalize per 1,000 residents
Here is a question I could not answer from the headlines: which European countries are actually losing people the fastest, in absolute terms or per…
When should you publish a dev post? I counted, and JP vs EN are mirror images
Let me confess something a little creepy. I have a habit of peeking at other people's dev posts. Not stealing the writing — relax. I run a tiny read…
Pandas vs SQL, when to use each
Pandas and SQL do a lot of the same things: filter rows, group, aggregate, join. So analysts reasonably ask which to learn and when to use which. Th…
Starting with Excel: How it transforms data to insights.
Introduction Excel is a powerful spreadsheet program developed by Microsoft that is used to calculate, organize and analyze data. It provides a way…
How Excel is Used in Real-World Data Analysis
When you think of a data analyst, you might picture someone staring at lines of complex code or navigating futuristic, enterprise-level software. Bu…
I scraped 50,000 G2 reviews to map the 2026 SaaS Battlecard Atlas
The 2026 SaaS Battlecard Atlas: What 50,000 G2 Reviews Reveal About 25 of the Most-Used B2B Tools A few weeks ago I got tired of guessing which B2B…